01925nas a2200301   4500000000100000008004100001260000900042653001300051653001500064653002900079653002900108653001100137653001300148653001200161653001500173100001400188700001500202700001000217700001100227700001700238700002500255245007700280856008300357300001000440490000700450520115200457022001401609       1970                            d  c197010aAntigens10aCell Count10aFalse Negative Reactions10aFalse Positive Reactions10aHumans10aLepromin10aleprosy10aSkin Tests1 aHANKS J H1 aNakayama T1 aAbe M1 aTUMA M1 aBechelli L M1 aMartinez Dominguez V00aStudies towards the standardization of lepromin. Progress and prospects.  uhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC2427501/pdf/bullwho00216-0054.pdf  a703-90 v423 a<p>Because of the wide range of concentrations of Mycobacterium leprae in existing lepromins the authors studied methods of producing a standardizable lepromin containing 160 million bacilli/ml. The effects of using different dilutions of lepromin on the incidence of false-positive reactions were also studied.Progress reported includes a convenient method for preparing large batches of non-sedimenting lepromin, which is directly suitable for microscopic counting of Myco. leprae cells; and a validation of current methods for microscopic enumeration of Myco. leprae. Skin tests with diluted lepromins have demonstrated that dilutions up to 1:16 increase progressively the ability to distinguish between lepromatous and tuberculoid leprosy. This work has provided further evidence that 20 million bacilli/ml (a 1:8 dilution of the initial lepromin) should produce adequate Mitsuda reactions in general populations, provided that 3-mm reactions are taken as the criterion for 1+ positivity. The net effect of these findings is equivalent to expanding the world supply of lepromin by 8 times.Recommendations for further research are proposed.</p>  a0042-9686